Photovoltaic plant, in particular a ground photovoltaic plant

ABSTRACT

The present invention relates to a photovoltaic plant including a plurality of units each having at least one respective photovoltaic panel, a support structure of the plurality of units designed to support the latter at a distance from the ground (GR).

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a photovoltaic plant, in particularground-based comprising a plurality of units each having at least onerespective photovoltaic panel.

STATE OF THE PRIOR ART

The solar trackers are devices that, through appropriate mechanicalmovements, allow to “track” the apparent movement of the sun in the skyor at least to orient one or more photovoltaic panels in a favourablemanner with respect to the sun rays. Clearly, the main purpose of atracker is to maximize the efficiency of the device hosted on board.

In the photovoltaic field, the panels mounted on a tracker are generallyarranged geometrically on a single panel, so that a tracker is notrequired for each single panel.

Based on their construction characteristics, the solar trackers aredivided according to:

-   -   degrees of freedom offered;    -   power supplied to the orientation mechanism;    -   type of electronic control.

The solar trackers can offer the panel uniaxial or biaxial freedom ofmovement.

Single-axis photovoltaic trackers are devices that “track” the sun byrotating around a single axis. Depending on the orientation of thisaxis, four types of trackers can be distinguished: tilt trackers, rolltrackers, azimuth trackers and polar axis trackers.

Tilt or “pitch” trackers, which are the simplest solar trackers to makeand also the cheapest, rotate around an axis in an east-west direction.

The roll trackers aim to follow the sun along the celestial vault in itsdaily path, regardless of the season of use. In this case the rotationaxis is north-south, while the height of the sun with respect to thehorizon is not a parameter that is considered.

The azimuth trackers rotate around a vertical axis perpendicular to theground. The panels are mounted on a rotating base coplanar to the groundwhich, by means of a servomechanism, follows the movement of the sunfrom east to west during the day but, unlike the tilt and roll trackers,without ever changing the inclination of the panel with respect to theground.

The polar axis trackers rotate, with the aid of a servomechanism, aroundan axis parallel to the north-south axis of the earth's rotation (polaraxis), and thus inclined with respect to the ground.

Biaxial photovoltaic trackers have two axes of rotation, usuallyperpendicular to each other. Two very common types of biaxial trackersare known, which differ in the different orientation of the rotationaxes: the azimuth-elevation ones and the tilt-roll ones.

The azimuth-elevation trackers, which track the sun assisted by acomputer calculating the predicted position in the sky or by a lightsensor that controls the motors, have their main axis of rotationvertical with respect to the ground and the secondary axis perpendicularto it.

The tilt-roll trackers have the main axis parallel to the ground, whilethe secondary one is normally perpendicular to the primary axis.

The choice of the tracking system depends on many factors, including thesize and characteristics of both the structure and the place ofinstallation, the latitude and the local weather and climaticconditions. Typically, biaxial trackers are used in small residentialinstallations and in countries that enjoy very high incentives. On theother hand, in other cases and for large photovoltaic parks, single-axisroll trackers are indicated, to take advantage of the low costs, as wellas the simplicity and robustness of the installation, which allows largescale savings in the face of a significant improvement in production ofenergy, especially in the afternoon. Uniaxial azimuth trackers, on theother hand, are suitable for high latitudes, where the sun does notreach great heights in the sky.

While requiring simple maintenance consisting of an annual inspectionand lubrication (as well as a painting of their structure, typicallymade of steel), the solar trackers inevitably encounter mechanicalproblems deriving from the wear of servomechanisms and moving parts thatoccur over time, especially in highly corrosive environments such asthose close to the sea or in polluted industrial locations, withconsequent production drops or implant interruptions. In fact, themechanical parts of the trackers are not very stressed, but subjected tosevere atmospheric conditions for at least 20 years. For this reason,tracking systems based on hydraulic mechanisms are generally preferableto those using electric motors, which are more easily oxidizable andsubject to the need for their replacement. Therefore, the mostprofitable use of solar trackers is that in large ground systems, thatis, in systems of many tens of KW or higher than MW.

Ordinary maintenance is generally simple, and in the photovoltaic fieldbenefits from a lower sensitivity of the photovoltaic effect to the dustdeposited on the surface of the modules, thanks to the best averageangle of incidence of sunlight. The whole system must also be designedto withstand the stresses due to wind load, which can be easilycalculated.

Tracking systems have a price per kW of installed power that isnecessarily higher than those with fixed mounting, since they havemoving components, therefore subject to wear and requiring control unitsdriven by computers or sensors. In addition, they require a largersurface area to prevent the modules of a system from shading each other.

Finally, static problems must always be taken into account, since,clearly, rotating components require more complex housings, compared topieces of equal stability mounted on a fixed support.

The favourable geographical position, a high percentage of directradiation and the availability of large surfaces have so far been themain success factors for tracker manufacturers, but the incentive ratesare very important.

Similar apparatuses can only be mounted with cranes and requirefoundations with volumes of approximately twenty cubic meters. Theforces that these systems have to withstand, which is especially truefor bearings and motors, are considerable even in the absence of wind.Most trackers have usually wind sensors and automatically move to asafety position when wind loads threaten the integrity of theirmechanics. However, in some systems, this arrangement is not provided(or in any case only in a limited way).

If the modules are mounted at a fixed angle and rotate only on thehorizontal plane, it is logically not possible to bring them to ahorizontal position: in this case, the sole possible solution is toposition the tracker in such a way that it offers the wind its shortestside.

In any case, the wind problem is of fundamental importance. It is notjust the risk of a total loss, but first of all the insurance premiumsrelated to the insurance of the systems, and secondly of usury.Components that are constantly running near their load limit alsorequire more frequent repairs or replacements, which increases costs perKWh.

The result is a clear trend towards the use of uniaxial systems; whichyield a lower energy production than biaxial ones, but they are alsosignificantly cheaper to produce, as well as being less prone tofailures.

US2015214885 concerns a photovoltaic plant with a series of photovoltaicunits operated by the same motor, so that by activating this motor it ispossible to substantially control the inclination of the units at thesame time.

The motion is transmitted to the photovoltaic units by the engine bymeans of a plurality of motion transmission rods, which rods are offsetto each other and connected by means of cardan joints.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new photovoltaicplant, in particular a ground photovoltaic plant.

Another object of the present invention is to provide a plant asaforementioned that guarantees optimal exploitation of solar energy andtherefore high efficiency.

Another object of the present invention is to provide a plant asindicated above which requires less energy for the respective actuationthan the solutions proposed so far.

Another object of the present invention is to provide a groundphotovoltaic plant equipped with respective very precise and reliablesystems for positioning panels.

Another object of the present invention is to provide a groundphotovoltaic plant that is not bulky and which has a low visual impact.

Another object of the present invention is to provide a groundphotovoltaic plant with support units for the photovoltaic modules thatare simple and economical to make and at the same time more resistantand lighter than traditional ones.

Another object of the present invention is to provide a groundphotovoltaic plant which is less affected by problems related to windthrust.

Another object of the present invention is to provide a groundphotovoltaic plant that compromises or modifies the conformation andquality of the installation ground less than the plants proposed up tonow.

Another purpose of the present invention is to provide a groundphotovoltaic plant that allows for quick and easy assembly, inspectionor maintenance.

According to one aspect of the invention, a plant according to thepresent application is provided.

According to another aspect of the invention, a group according to thepresent application is provided.

The present application refers to preferred and advantageous embodimentsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be more evident fromthe description of an embodiment of a plant, illustrated as anindication in the accompanying drawings in which:

FIG. 1 is a slightly top perspective view of a plant according to thepresent invention,

FIG. 2 is a perspective view slightly from above of a row of groups withsupport units for photovoltaic panels according to the present inventionof the plant of FIG. 1 ,

FIG. 3 is a side view of the row of FIG. 2 ,

FIGS. 4, 5, 6 and 7 are side, front and slightly perspective from belowand from above, respectively, views of a group according to the presentinvention for the plant of FIG. 1 ,

FIG. 8 is a front view of the group of FIG. 4 without photovoltaicpanels,

FIG. 9 is a front view of the unit of FIG. 4 in an inclined position inan east-west direction,

FIGS. 10 and 11 are side views of a unit according to the presentinvention for a plant of FIG. 1 with respective details concerning therespective rotation shaft of the photovoltaic panels.

In the accompanying drawings identical parts or components are indicatedby the same reference numbers.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the attached figures, a photovoltaic plant 1 has beenillustrated, in particular, but not necessarily, on the ground or thatcan be installed on the ground comprising a plurality of units 2 eachhaving at least one respective photovoltaic panel 3, if desired also aplurality of panels, for example two, three, four, five or more.

If desired, the photovoltaic panels 3 have a plan configuration which issubstantially rectangular or square.

Preferably, the photovoltaic panels 3 of a respective unit are parallelto one another and side by side with respective edges adjacent and incontact with those of adjacent panels.

The panels can have any suitable dimensions, for example a length ofabout 1.5-2.5 meters, if desired about 2 meters, and a width of about0.8-1.2 meters, for example 1 meter.

The panels 3 can be of a suitable type, for example with peak powershigher than 400 Wp (Watt peak=Peak power of the photovoltaic panel), ifdesired mono and poly crystalline with 72 power cells, substantiallyequal to 435 Wp.

Clearly, panels with different dimensions or powers could be provided.

If desired, the panels can also have active double-sided cells, whichtherefore absorb light from both their faces.

In any case, in the present description, when the detection face of thepanels 3 is indicated, reference will be made to the upper, in use, faceof the photovoltaic panels or of the respective cells, thus notconsidering the possible presence of a possible lower detection face.

The plant 1 then includes a support structure 4 of the units 2 designedto be driven (in part) or constrained to the soil or ground GR andsupport the units 2 at a distance from the soil or ground GR, forexample at about 1-2 meters from the soil.

Preferably, one, some or each unit 2 is/are, in use, inclined in such away that the respective photovoltaic panel(s) 3 or rather the respectiveactive detection face is facing or can be positioned so as to be facingtoward south, therefore with its own lower end 3 a closer to the souththan a respective upper end 3 b, which is clearly at a higher level thanthe lower end 3 a.

In this case, of course, if the photovoltaic panels are traditional, andthus with cells with one active face only, then this face is, in use,facing (upwards) and southwards.

If desired, the units 2 are inclined so that the angle A (see FIG. 5 )delimited between the photovoltaic panels 3 (or rather between the mainlying plane of the active detection face of the panels 3 or of therespective cells) and a horizontal surface underlying the same is equalto about 10°-20°, if desired about 15°. This naturally applies if thepanels 3 are not inclined towards east or west, but, if, as will be saidlater, such inclination is foreseen, then the angle A is that betweenthe aforementioned horizontal surface and a straight line obtained byjoining the lower end 3 a, at one side of the unit or better of therespective panel 3, with the upper end 3 b, always at this side.

Preferably, the inclination towards south cannot be changed. When thisinclination is fixed, the whole plant is rendered compact and with a lowvisual impact.

In this regard, it was possible to assess that inclinations greater thanthose indicated above would not give rise to significant increases inelectricity production.

Regarding this, if the ground GR on which the plant is mounted has ahorizontal upper surface GR1 or substantially horizontal, then thisangle is also the angle between the photovoltaic panels 3 (or betterbetween the main lying plane of the active detection face of the panels3 or of the respective cells) and such upper surface GR1 and is equal tothe above indicated value. This applies, as above indicated, in acondition with no inclination towards east or west.

Clearly, all the panels 3 must not necessarily have the sameinclination, as they may have different inclination angles.

In this text, the terms “south”, “north”, “east” and “west” refer to thecardinal points or directions.

The plant 1 is then provided with at least one motor 5, electric,hydraulic or pneumatic, and with motion transmission means 6 from themotor 5 to at least two units 2, so that by activating one motor 5 onlyit is possible to control the inclination substantially simultaneouslyin an east-west direction of at least two units 2.

This expedient is clearly designed to ensure tracking of the sun.

The motor 5 can be for example, but not necessarily a direct currentmotor, if desired a 24 V motor.

The motor 5 together with the motion transmission means 6 can bedesigned to vary the inclination in an east-west direction, preferablyaround an axis in a north-south direction, of the units 2, if desiredfor an angle or arc of angular displacement maximum greater than 80°,for example equal to a value between about 100° and about 130°.

More specifically, the motor 5, thanks also to the transmission means 6,is designed to cause the photovoltaic panels 3 to perform adiscretionary tilting movement (see FIG. 9 ) from a starting position,for example with the panels (or the respective detection face) facingtowards east with an inclination of about 20°-30°, if desired 25° withrespect to the east, to an arrival position, for example facing towardswest with an inclination of about 20°-30°, if desired 25° with respectto the west, passing through a horizontal position at noon.

Naturally, the motor 5 is capable of imparting to the panels a pluralityof inclinations in a predefined range, for example greater than 80° orequal to or less than 100° or 130°, not only therefore at the extremesof the inclination range or at the starting and ending position.

If desired, the starting position is imposed on panels 3 in the earlyhours of the morning, while the arrival position is in the evening. Inthis case, at noon, the panels 3 could be horizontal, and thus withtheir sides substantially at the same level.

As it will be understood, in order to tilt the panels 3 in an east-westdirection, a first side 3 c of the panels 3 must be lowered and/or theother or second side 3 d must be raised. In this case, one side at thelower end 3 a will be, at the end of the inclination, lower than theother side at the lower end 3 c and the same applies to the upper end 3b.

In this regard, the angle of inclination is defined by the straight linepassing through the two sides 3 c, 3 d of the lower end 3 a or for thetwo sides 3 c, 3 d of the upper end 3 b and a horizontal surfaceunderlying the panels 3.

In this regard, if the ground GR on which the plant is mounted has ahorizontal or substantially horizontal upper surface GR1, then thisangle is also the angle between the lines as now defined and this uppersurface.

So far as the horizontal position is concerned, it is a position inwhich both sides 3 c, 3 d of the lower end 3 a are at the same level andthe same applies to the two sides 3 c, 3 d of the upper end 3 b.Therefore, in this position the detection face is preferably nothorizontal, but it faces towards south.

If desired, to change again the inclination, one could move the panelsbackwards and then, if desired, make them incline in the opposite way,by lowering the second side of the panels and/or lifting the first side.

Advantageously, the motion transmission means 6 comprise at least oneshaft 7 arranged or aligned in a north-south direction, which shaft canbe actuated in rotation by the motor 5 and is integral in rotation withtwo or more units 2, so that by activating the motor the shaft 7 is madeto rotate and thus the inclination or angular displacement towards eastor west of these units 2 is controlled and viceversa. If desired, amotion decoupling component from one or more units to the shaft 7 can beprovided for, so that the latter can transmit motion to the units, butthe reverse does not apply.

With regard to this aspect, the shaft 7 rotates around a respective mainaxis of longitudinal extension x-x (see FIG. 6 ), which is preferablythe north-south axis.

Moreover, as it will be understood, the rotation of the shaft in onedirection determines the inclination of the panels towards east, while arotation of the shaft in the other direction determines the inclinationof the panels towards west.

Of course, the rotations of the shaft are not complete rotations (360°),but a angle much lower than a complete rotation, if desired between 10°and 20°, 30°, 40° or 50°.

The motion transmission means 6 may also include a plant of bracketsand/or rods 8 a, 8 b arranged to transmit the rotation from the shaft 7to the units 2 or better to the photovoltaic panels 3.

If desired, this system may comprise for one, some or each unit 2 atleast a pair of brackets 8 a integral in rotation or angulardisplacement with the shaft 7 and protruding from positions thereofoffset along the respective main extension longitudinal axis x-x and atleast one pair of rods 8 b each on one side pivoted or articulated to abracket 8 a and on the other to a respective portion of a respectiveunit 2. If desired, said rods 8 b are articulated to a respective unit 2by means of spherical joints 8 c or of another type.

The brackets 8 a can have, in use, a substantially horizontalarrangement, while the rods 8 b rise upwards starting from the brackets8 a or better from a section or end of the same distal from the shaft 7.Clearly, during the inclination of the units 2 towards east or west, thearrangement of the brackets 8 a and rods 8 b varies slightly.

The rods 8 b can be inclined so as to have an upper, in use, end whichis closer to the south of the respective lower, in use, end.

The brackets 8 a can for example be integral or in one piece with asleeve fitted and keyed or otherwise integral in rotation around theaxis x-x on a respective section or section 7 a of the shaft 7.

Preferably, the two rods 8 b of o for a respective unit 2 have differentlengths because they are designed to be constrained in offset sectionsalong the axis x-x of a respective unit 2. Therefore, considering thatthe unit 2 is inclined so as to ensure that the respective photovoltaicpanel(s) 3 (or rather the respective detection face) is facing towardssouth, these rods 8 b will have a length greater than the other and morespecifically the length proximal to the north and distal to the southwill be longer and viceversa.

Such a condition can also occur for the two brackets 8 a, whichtherefore can have different lengths.

The motor 5 can instead be supported by a support component or frame 9integral with the support structure 4 and a lever or a pair of levers 10of the motion transmission means 6 from the motor 5 or by an actuator 11controlled thereby to the shaft 7 can then be provided. The lever orpair of levers 10 is, on the one hand, pivoted to the stem 11 b of suchactuator 11, if desired to a tip of the same and on the other it isintegral with the shaft 7, for example fixed or in a single piece with abush 7 b fitted and keyed onto a section of the shaft 7 or in any caseconstrained so as to be integral in rotation with the latter around theaxis x-x.

The motor 5 can be supported at a height of about 0.8-1.2 meters, ifdesired 1 meter from the soil GR.

As already partially indicated above, at least one actuator 11 can beprovided, if desired linear, with a cylinder 11 a and a stem 11 b thatcan be inserted/disinserted into/from the cylinder 11 a, in which casethe motor 5 is arranged to control the insertion/disinsertion of thestem 11 b into/from the cylinder 11 a. The stroke of the actuator 11 canbe any suitable one, for example 100-200 mm, if desired 160 mm.

The actuator 11 can be arranged with an upper cylinder 11 a and stem 11b arranged to come out towards the bottom of the cylinder 11 a.

If desired, in the case of an electric motor, a gearmotor is providedfrom the motor 5 to the actuator 11, so as to determine a specific speedof advancement or disinsertion/insertion of the stem 11 b in/from thecylinder 11 a, advantageously equal to about 3-6 mm/s, for example 4mm/s. The actuator 11 or the motor-actuator unit can also be equippedwith a position transducer and/or limit switch. This transducer is ofcourse designed to control the position and/or the limit switch of therespective stem 11 b. If a position transducer is provided, then theactuator can also be equipped with a digital output for reading thestroke of the stem 11 b both in push and pull.

The actuator 11 is preferably suitable for performing intermittent workcycles and very reduced and repetitive displacements over time, thisbeing achieved thanks to a high number of engine revolutions, lowinstalled power, large reduction ratio and very small speed ofadvancement of the stem, for example as indicated above.

Of course, the extension/retraction of the stem 11 b from/into thecylinder 11 a is gradual and can be locked in position by the engine 5in a series of trims or positions between the maximum retractionposition and the maximum extension position.

The actuator 11, if provided, can even be supported by the supportcomponent or frame 9 or by another component integral with the supportstructure 4.

According to the non-limiting embodiment illustrated in the figures, thecylinder 11 a of the actuator 11 is constrained, for example by means ofa screw or bolt or any other suitable means to the support component orframe 9, while the motor 5 is mounted in such cylinder 11 a andsupported thereby.

With such a structure, by activating the motor 5, this determines theextension or retraction of the stem 11 b and thus the angulardisplacement of the lever or levers 10, thereby determining the rotationin one direction or the other of the shaft 7 and therefore theinclination or angular displacement of two or more units 2 and of therespective photovoltaic panels 3 towards east or west (depending on thedirection of rotation of the shaft). With reference to the non-limitingembodiment illustrated in the figures, the rotation of the shaft 7determines the displacement of the system of brackets and/or rods 8 a, 8b designed to transmit the rotation from the shaft 7 to the units or toa respective unit 2.

In this regard, the rotation of the shaft 7 causes an angulardisplacement of the brackets 8 a and therefore of the rods 8 b, whichtransmit the motion to a respective unit 2.

As regards in particular the structure of the units 2, one or more ofthe same can include at least two beams or longitudinal members 13offset from each other and supporting at least one photovoltaic panel 3.

If desired, but not necessarily, the longitudinal members 13 are placedwith the respective main extension direction, in a transverse ororthogonal direction to the shaft 7, for example in an east-westdirection. In this case, the beams or longitudinal members 13 can beoffset in the direction, in use, north-south.

The panels 3 are fastened to the longitudinal members 13 by any suitablemethod, for example screws, bolts, adhesive or other.

In this case, this unit 2 could also not comprise bridge connectingtransverse elements of the longitudinal members 13. The panels 3 wouldtherefore constitute the connection structure between the two beams orlongitudinal members 13. The longitudinal members 13 would in this casebe mechanically connected only by means of one or more panels 3.

With reference to this variant, one or more units 2 can compriseterminal retaining means 14 for the panels 3 constrained at the ends ofthe longitudinal members 13. The terminal retaining means 14 can includesuitably shaped or folded and constrained plates, if desired by means ofscrews, bolts or other means, to the ends of the longitudinal members 13and arranged to wrap a respective section of the edge of the panels 3.

The terminal retaining means 14 can also be designed to pack and keepthe panels 3 on the longitudinal members.

Preferably, for each unit end retaining means 14 are provided which actat least on two opposite sides or ends of the panels so as to clampthem.

Even more preferably, if at least one unit comprises several panels 3,if these are placed side by side, the retaining means 14 act on theedges, in use, external of the panels parallel or substantially parallelto the edges of abutment of the panels side by side so as to act, asindicated above, as packing means for adjacent panels, whereby suchmeans press from the outside a panel in the direction of the otherpanels of the respective unit 2.

Moreover, the longitudinal members 13 can have a T-shaped configuration,in which case the unit 2 includes reinforcement brackets 15 of thelongitudinal members 13 placed in one or both of the seats delimitedbetween inclined or orthogonal sections of the T.

In the event that more panels 3 are provided in at least one unit, thensupport and hooking means 14 a between panels can be included for thisunit. Said support and hooking means 14 a can be mounted on andsupported by one or both longitudinal members 13, at the zone ofabutment of edges of adjacent panels.

The longitudinal members 13 can be obtained, for example, from a foldedsheet or in another suitable way.

Therefore, preferably the metal transverse elements normally used in thesupport structures for photovoltaics are not provided in the units 2,and thus at least two longitudinal members or beams only are usedwithout apparent junctions between them except the panels themselves; ifdesired the plant is equipped with suitable safety constrain applied onthe units.

This solution aims to obtain the lowest possible material consumption.

If the longitudinal members 13 and the rods 8 b are provided, then thelatter can be articulated, if desired but not necessarily by means ofspherical joints 8 c, to the longitudinal members 13. More particularly,according to the embodiment illustrated in the figures, the pairs ofrods 8 b of or for a respective unit 2 are each articulated to arespective longitudinal member 13. In this regard, the line connectingthe pivot points of the rods 8 b of a unit can delimit theaforementioned angle A with a straight line, preferably horizontal,subtending this connecting line.

A unit 2 as described here is the subject-matter of the presentinvention even independently by the plant and the other elements hereindescribed.

Advantageously, the plurality of units 2 of the plant 1 comprises one ormore rows 1 a with from five to fifteen units, if desired ten units,each supporting at least one photovoltaic panel 3 or better a pluralityof panels, for example two, three, four, five or more side by side and,preferably, packed panels.

In this case, the motion transmission means 6 are designed to transmitthe motion from the same engine 5 to all such units 2 of the plant or ofa respective row 1 a (if more rows of units are provided, as will bebetter described later), so that by operating the motor 5 it is possibleto control substantially simultaneously the inclination in the east-westdirection of the (from five to fifteen) units 2 of the same row 1 a.

With reference to the embodiment shown in the figures, the motor 5 ismounted at a unit 2 placed in an intermediate position between the otherunits 2 of the plurality or better (it is mounted) on the supportstructure 4 of this unit 2.

If desired, the plant 1 comprises at least two rows or series 1 a ofunits 2, each row 1 a including a plurality of units 2, in which casethe plant further comprises at least two motors 5 each designed tocontrol substantially simultaneously the inclination in the directioneast-west of all the units 2 of a respective row 1 a. The rows 1 a areclearly offset from each other, in particular in an east-west direction,if desired so that the panels 3 of adjacent and subsequent rows are at adistance greater than one meter, if desired between 2 and 3 meters, forexample about 2.5 meters.

In this case, at least two shafts 7 parallel to each other arepreferably provided, advantageously arranged or aligned in a north-southdirection, each shaft 7 being integral in rotation or better in angulardisplacement with all the units 2 of a respective row 1 a, so that byrotating the shaft 7 the inclination or angular displacement towardseast or west of these units 2 is controlled and viceversa.

Advantageously, the shafts 7 of adjacent rows are not kinematicallyconnected, and thus the motion of one shaft 7 is not imparted to theother and viceversa.

According to the embodiment illustrated in the figures, six rows 1 aeach with ten units 2 are provided, which include a plurality of (forexample three, four, five) panels 3 and six motors 5 are provided eachfor the inclination or angular displacement drive, if desired by meansof respective six shafts 7, of the units 2 of a respective row 1.

Basically, preferably, a respective motor 5 and a respective shaft 7 areprovided for each row 1 a.

If desired, the pitch between the individual units is about 2000-4000mm, for example 3000-3500 mm, if desired 3150 mm in the north-southdirection and about 6000-7000 mm, for example 6500 mm in the east-westdirection.

“Natural” passageways between the rows can therefore be delimited, whichwill ensure easy access both during the construction of the plant andduring maintenance.

A plant 1 as described above (non-limiting embodiment of the invention)can ensure for example 1 MWp.

In the future, with the increase in the efficiency of the panels 3 itwill also be possible to obtain a decrease in the number of units 2necessary for the construction of a single plant, for example of 1 MWp,and this reducing the use of agricultural land currently required (forexample about 12,000 square meters) with a significant reduction incosts for the individual plant.

So far as in particular the shaft 7 is concerned, it may include severalsections 7 a connected to each other and removably or not connected, ifdesired by means of suitable joints 16.

The sections 7 a are naturally aligned along the axis x-x, consideringthat the shaft 7, and therefore all the sections 7 a making it, rotatesaround the main longitudinal axis of extension x-x.

With regard to this aspect, each section 7 a could be hollow, at leastat at least one of its ends, and have holes or a slot 7 c at one or bothof its hollow ends, while the joints 16 have one or a pair of holes orslots, so that it is possible to align one of these holes or slots witha hole or slot 7 c of a first section 7 a and the other hole with a holeor slot 7 c of a second section 7 a adjacent and subsequent to thefirst.

In order to constrain the sections 7 a to each other, it would thensuffice to insert screws or bolts 7 d in these aligned holes/slots andtighten each joint 16 to two respective sections 7 a by means of thesescrews or bolts 7 d.

Instead of a joint 16 one could also use sections 7 a with a hollow andsuitably perforated end and the slot 7 c at the other end.

Of course, in order to allow small displacements between the sections 7a, only one of the two respective sections 7 a could be fixed at eachjoint 16, while the other could have a respective end mounted slidinginside or around the joint 16, so that one would in fact have a slidingjoint. The same is true if there are no joints.

If desired, in this case, the sections 7 a would be movable or mountedsliding one with respect to the other, for example by an entity equal toabout 0.5-5 cm in the direction of the main extension axis x-x of theshaft 7.

Relatively instead to the support structure 4, it can include, forexample poles 4 a, 4 b, if desired in prestressed concrete, which arefixed in the ground, with vertical arrangement, according to thenon-limiting embodiment shown in the figures.

Two poles 4 a, 4 b can be for example provided for each unit 2, at thetop of each of which a respective longitudinal member 13 is hingedeither directly or by interposition of a suitable constraining componentor group of components 17.

In the case of two poles 4 a, 4 b for one unit 2, they can comprise afirst higher pole 4 a designed to support a respective unit 2 at anupper end 3 b of the panels 3 and a second lower pole 4 b designed tosupporting a respective unit 2 at a lower end 3 a of the panels 3 ofunit 2. The first pole 4 a is driven into the ground GR in an areacloser to the north than the second pole 4 b.

This expedient ensures the inclination of units 2 towards south.

The poles 4 a, 4 b can have any suitable length, such as between 1 and 2meters, if desired a first pole of about 1400-1600 mm, for example 1500mm and a second pole of about 1800-2000 mm, for example 1850 mm, bothwith a section driven into the ground for 300-800 mm, if desired about500 mm.

The two poles 4 a, 4 b are suitably spaced apart, for example by about1-1.5 meters, if desired, about 1.2 meters.

The poles can be driven into the ground using a pile-driving machine,for example with controlled vibration and, if desired, equipped with GPSpositioning (starting from a known topographical point), which canguarantee a maximum error of 1 cm in the insertion and an error on thevertical of the pole of maximum 0.2°, which errors are clearlyacceptable without compromising the functionality of the rotationmechanism.

The section of these poles 4 a, 4 b can be small, for example 70×70 mmand they are capable of effectively replacing the expensive foundationworks normally required in similar applications.

With reference to the non-limiting embodiment shown in the figures, thegroup of constraining components 17 comprises two first plates 18mounted one opposite the other with respect to an upper end of arespective pole 4 a and linked together by means of first screw or studelements 19. One of the plates 18 has also an appendix 18 a to which arespective longitudinal member 13 is hinged by means of a respective pin20, if desired at the center line or intermediate zone of thelongitudinal member 13.

Two second plates 21 are provided for connecting the shaft 7 to thepoles 2 a, again according to the non-limiting embodiment illustrated inthe figures, which plates 21 are mounted one opposite to the other withrespect to an intermediate section of a respective pole 4 a and fixedone to the other by means of second screw or stud elements 22.

One or both the second plates 21 can also have a projecting section 21 adelimiting a hole for the passage of the shaft 7 or rather of a sectionor segment 7 a of the same.

If desired, the supporting component or frame 9 can have a structuresimilar to that described for the group of constraining components 17.

In order to prevent the shaft 7 from sliding with respect to the poles 2a, the plant 1 can be provided with locking rings 23 arranged at theholes delimited by the second plates 21. This expedient can be providedat one or both poles 4 a, 4 b.

Moreover, the poles 2 a can be provided with anti-break-in brackets 24at the bottom of the same, designed to be, in use, close to or incontact with the driving soil or ground GR.

A plant according to the present invention must then be clearly equippedwith one or more inverters to convert the direct electricity producedinto alternating current.

The plant could then include a control unit designed to control therespective components, in particular the motor 5 to appropriately vary,in particular during the day, the east-west inclination of the units 2and thus of the respective panels 3.

Moreover, the plant can then provide markings in the ground for thepositioning of the ducts for housing the electrical power cables thatwill connect the inverters to the medium voltage substation.

It should also be noted that the subject-matter of the present patentapplication also independently of the aforementioned plant is a groupfor a ground photovoltaic plant comprising a unit 2 as described above,a support structure 4 as described above arranged, in use, to supportthe unit 2 at a distance from the ground GR, a motor 5 supported by asupport component or frame 9 integral with the support structure 4,motion transmission means 6 from the motor 5 to the unit 2 comprising ashaft 7 or a section 7 a of a shaft 7, so that by operating the motor 5it is possible to control the inclination of the unit 2.

This assembly can comprise components described above, for example anactuator 11, while the motor 5 can be an electric motor with a gearmotorfrom the motor 5 to the actuator 11, so that the speed of advancement ordisinsertion/insertion of the stem 11 b in the cylinder 11 a is about3-6 mm/s, for example 4 mm/s.

A system of brackets and/or rods 8 a, 8 b as indicated above can then beprovided in this group.

As it will be possible to ascertain, a plant according to the presentinvention has thus a single drive motor and, preferably, a single driveshaft which connects and drives several units, even ten or more, eachprovided with two, three, four or more photovoltaic panels, for examplewith high efficiency.

The single motorization of several units, makes it possible tosignificantly reduce the costs for tracking the sun, if one considers,for example, that in order to drive a 1000 KWp system, the use of even afew actuators is sufficient, for example 57.

Therefore, owing to the present invention, a monoaxial solar tracker isactually obtained.

The southward inclination of the panels makes the plant efficient and,in particular when the inclination is fixed, ensures limited overalldimensions and low visual impact.

Another important, although not essential, aspect of the presentinvention is the preparation and possible use of new photovoltaic unitsor panels that act as a connecting structure between two main beams orlongitudinal members, preferably without metal transverse elementsnormally used in photovoltaic support structures. It is thereforepossible to use only two bent sheet beams without junctions between themother than the one obtained owing to the panels themselves.

This expedient allows, together with the other aspects discussed, toreduce the necessary material.

Another functional solution for reducing costs is the possible use ofprestressed concrete poles, which are particularly suitable when theyare subjected to bending resulting from the thrust of the wind.

In this regard, if, for example, the panels were at a maximum height ofabout 1600 mm at the highest point and a minimum height of about 1060 mmat the lowest point, by rotating them towards east and west the highestpoint would be positioned at about 2422 mm, but the opposite corner ofthe units on the same side would drop to 1853 mm from the ground. Itwill be understood that in this case, the wind stress on the concretepoles and more generally on the metal structures of the plant is lower.Furthermore, concrete poles have a very low cost as well as theirpositioning during the installation phase of the plant.

From an environmental point of view, if we exclude the tracing of theground for the positioning of the ducts for housing the electrical powercables that will connect the inverters to the medium voltage substation,there is no need to carry out other works that could compromise ormodify the conformation and quality of the bottom where the photovoltaicplant will be installed.

Owing to the present invention it is therefore possible to reduce theoverall cost of a photovoltaic plant, so as to make the energy producedby the photovoltaic plant competitive even with that produced by fossilsources, creating the so-called “market parity”.

Of course, the present invention can be used for the construction ofplants of any power, both 1 MWp but also higher, for example of 2, 3, 5,10 or more MWp. The substantial difference between the different powersizes lies in the authorizations necessary for the construction of thework, or in the PAS (procedure similar to SCIA) for plants up to 1 MWp(999 KWp) simple to obtain (on average 30/60 days) and the longer andmore complex Single Authorization for plants over 1 MWp to obtain (it isalso necessary to wait years before receiving approval from the relevantregion).

In any case, depending on the maximum power of the plant to be built, itis sufficient to replicate and appropriately combine a certain number ofstandard units as described above.

Changes and variants of the invention are possible within the scopedefined by the claims.

The invention claimed is:
 1. A photovoltaic plant comprising: aplurality of units each having at least one respective photovoltaicpanel, a support structure of said plurality of units designed tosupport the plurality of units at a distance from the ground, furthercomprising at least one motor and motion transmission means from said atleast one motor to at least two units, so that by activating only onemotor it is possible to control substantially simultaneously theinclination in an east-west direction of said at least two units,wherein said motion transmission means comprise at least one shaftarranged or aligned in a north-south direction, said at least one shaftbeing actuatable in rotation by said at least one motor and beingintegral in angular displacement or inclination with said at least twounits, so that by activating said at least one motor the rotation ofsaid at least one shaft is determined and thus the angular displacementtowards east or west of said at least two units is controlled, whereinsaid at least one shaft includes several sections connected to eachother, wherein said at least one shaft rotates around a respective mainaxis of longitudinal extension; further comprising at least one actuatorcomprising a cylinder and a stem, said stem being extendable from andretractable into said cylinder, and wherein said at least one motorcontrols the extension/retraction of said stem from/into said cylinder,wherein the extension/retraction of the stem causes angular displacementof at least one lever, said at least one lever having one end pivotablyconnected to the stem and an opposite end connected to the at least oneshaft, said angular displacement of the at least one lever causingrotation of the said at least one shaft to control the inclination inthe east-west direction of the at least two units and wherein saidmotion transmission means for at least one unit comprise at least onepair of brackets integral in rotation or angular displacement with saidat least one shaft and extending from positions of said at least oneshaft offset along the respective main axis of longitudinal extension,and wherein said motion transmission means further comprise at least onepair of rods, each rod having a first end pivotably connected to eachbracket and a second end connected to a respective portion of arespective unit.
 2. The photovoltaic plant according to claim 1, whereinat least one unit of said plurality of units is inclined so that said atleast one respective photovoltaic panel is facing or positioned so as tobe facing south, therefore with its own lower end closer to the souththan a respective upper end.
 3. The photovoltaic plant according toclaim 1, wherein said at least one motor is supported by a supportcomponent or frame integral with said support structure.
 4. Thephotovoltaic plant according to claim 1, wherein said at least one motoris supported at a height of about 0.8-1.2 meters above the ground. 5.The photovoltaic plant according to claim 1, wherein said motor is anelectric motor and a gearmotor is then provided for the motion from saidmotor to said at least one actuator, so that the speed of advancement orextension/retraction of said stem in said cylinder is about 3-6 mm/s. 6.The photovoltaic plant according to claim 3, wherein said actuator isequipped with at least one of a position transducer and a limit switch.7. The photovoltaic plant according to claim 1, wherein said rods arearticulated to a respective unit by means of spherical joints.
 8. Thephotovoltaic plant according to claim 1, wherein at least one unitcomprises a pair of beams or longitudinal members set apart from eachother and supporting said at least one photovoltaic panel.
 9. Thephotovoltaic plant according to claim 8, wherein said at least onephotovoltaic panel constitutes a connection structure between the pairof longitudinal members.
 10. The photovoltaic plant according to claim8, wherein at least one unit comprises terminal retaining means for saidpanels constrained at the ends of said longitudinal members.
 11. Thephotovoltaic plant according to claim 1, wherein said plurality of unitscomprise between five and fifteen units each supporting at least onephotovoltaic panel, said motion transmission means being designed totransmit motion from one same motor to all said plurality of units, sothat by activating said at least one motor it is possible to controlsubstantially simultaneously the inclination in the east-west directionof said five to fifteen units.
 12. The photovoltaic plant according toclaim 1, comprising at least two rows of units, each row including aplurality of units, said plant further comprising at least two motorseach designed to control substantially simultaneously the inclination inthe direction east-west of all units of a respective row of units. 13.The photovoltaic plant according to claim 12, wherein said rows areoffset from each other so that the panels of adjacent and successiverows are at a distance between 2 and 3 meters.
 14. The photovoltaicplant according to claim 1, comprising joints for connecting saidsections of said shaft, each section being hollow, at least at its ends,and having holes or a slot at one or both of its hollow ends, while thejoints have one or a pair of holes or slots, so that it is possible toalign one of these holes or slots of a joint with a hole or slot of afirst section and the other hole with a hole or slot of a second sectionadjacent and subsequent to the first, adjacent sections beingconstrained by screws or bolts inserted in these holes/slots aligned andtightening each joint to two respective sections by means of thesescrews or bolts.
 15. The photovoltaic plant according to claim 1,wherein said sections are mutually movable or mounted sliding relativeto each other by an amount equal to about 0.5-5 cm in the direction ofthe main extension axis of said at least one shaft.
 16. The photovoltaicplant according to claim 1, wherein said at least one motor is designedto vary the inclination in the east-west direction of said units by anangle or arc of maximum angular displacement greater than 80° .
 17. Thephotovoltaic plant according to claim 1, wherein said support structurecomprises poles made of prestressed concrete.
 18. The photovoltaic plantof claim 1, wherein each of said at least one photovoltaic panelcomprises active double-sided cells.
 19. A group for a groundphotovoltaic plant comprising: a unit having at least one respectivephotovoltaic panel, a support structure of said unit designed, in use,to support the unit at a distance from ground, at least one motorsupported by a support component or frame integral with said supportstructure so that said at least one motor is supported at the distancefrom the ground, motion transmission means connecting said at least onemotor to said unit, so that activating said at least one motor controlsthe angular displacement or inclination of said unit, said motiontransmission means comprising a shaft or a section of a shaft, saidshaft being operable in rotation by said at least one motor and beingintegral in angular displacement or inclination with said unit, so thatby activating said at least one motor the rotation of said at least oneshaft is determined and thus the angular displacement or inclination iscontrolled towards the east or west of said unit, further comprising atleast one actuator comprising a cylinder and a stem, said stem beingextendable from and retractable into said cylinder, and wherein said atleast one motor is operably connected to said stem to control theextension/retraction of said stem from/into said cylinder, wherein theextension/retraction of the stem causes angular displacement of at leastone lever, said at least one lever having one end pivotably connected tothe stem and an opposite end connected to the shaft, said angulardisplacement of the at least one lever causing rotation of the shaft tocontrol the inclination in the east-west direction of the unit, andfurther comprising at least one pair of brackets integral in rotation orangular displacement with said shaft or section of a shaft and extendingfrom positions of said at least one shaft offset along the respectivemain axis of longitudinal development, and further comprising at leastone pair of rods, each rod having one end pivotably connected orarticulated to one of said pair of brackets and a second end connectedto a respective portion of said unit.
 20. The group according to claim19, comprising at least one actuator having a cylinder and a stem whichcan be inserted into and disinserted from said cylinder and wherein saidat least one motor is designed to control the insertion/disinsertion ofsaid stem in/from said cylinder, wherein said motor is an electric motorand a gearmotor is then provided from said motor to said actuator, sothat the speed of advancement or disinsertion/insertion of said stem insaid cylinder is about 3-6 mm/s.
 21. A group for a ground photovoltaicplant comprising: a unit having at least one respective photovoltaicpanel; a support structure of said unit to support the unit at adistance from ground; at least one motor supported by a frame integralwith said support structure so that said at least one motor is supportedat the distance from the ground; motion transmission means connectingsaid at least one motor to said unit, so that activating said at leastone motor controls an angular displacement of said unit; said motiontransmission means comprising a shaft or a section of a shaft, saidshaft being rotatable by said at least one motor for causing the angulardisplacement of said unit, so that activating said at least one motorcauses a rotation of said at least one shaft, causing the angulardisplacement of the unit towards an east or west direction; furthercomprising at least one actuator comprising a cylinder and a stem, saidstem being extendable from and retractable into said cylinder, andwherein said at least one motor is operably connected to said stem tocontrol the extension/retraction of said stem from/into said cylinder,wherein the extension/retraction of the stem causes angular displacementof at least one lever, said at least one lever having one end pivotablyconnected to the stem and an opposite end connected to the shaft, andsaid angular displacement of the at least one lever causing the rotationof the shaft to control the inclination towards the east or westdirection of the unit, and further comprising at least one pair ofbrackets movably connected with said shaft and extending from positionsthereof offset along the respective main axis of longitudinaldevelopment, and at least one pair of rods, each rod having one endpivotably connected to one of said pair of brackets and an opposite endconnected to a respective portion of said unit.